Abstract:
The present invention provides a transceiver apparatus that permits miniaturization even when the antenna thereof is an unbalanced circuit and the transmitter circuit section and receiver circuit section thereof are balanced circuits. 
     The transceiver apparatus is constituted comprising: a semiconductor integrated circuit device that mounts on the same semiconductor chip a balanced receiver circuit  41  for receiving a received signal as a differential input and balanced transmitter circuit  52  for outputting a transmitted signal as a differential output, and that has at least two terminals  71,72  connected to connecting nodes that connect the balanced receiver circuit  41  and the balanced transmitter circuit  52 ; first and second capacitors C 2 ,C 3  connected to the terminals  71, 72  respectively; an external inductor L 1  connected to the first and second capacitors C 2 , C 3 ; a band pass filter  2  and an antenna  1  coupled to the first capacitor C 2 ; and a third capacitor C 1  connected to the second capacitor C 3.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a transceiver apparatus, and more particularly to a transceiver apparatus in which a transmitter circuit and a receiver circuit for processing transmitted and received signals respectively are balanced circuits. 
   2. Description of the Related Art 
   Transceiver apparatuses often employ a constitution in which the transmitter and receiver circuit sections thereof are balanced circuits. Such a constitution makes it possible to use differentiation to cancel out internal digital noise and the like which is superposed on transmitted and received signals, thereby permitting an improvement in the accuracy of the transmission and reception operations. 
   A representative constitution of a conventional high frequency signal transceiver apparatus in which the transmitter and receiver circuit sections thereof are balanced circuits is shown in  FIG. 3 . The conventional high frequency signal transceiver apparatus comprises an antenna  1  for transmitting and receiving digitally modulated high frequency signals, a band pass filter  2  for limiting the transmitted and received signals of the antenna  1  to a predetermined frequency band, a switch circuit  3  for allowing the antenna  1  to be shared by the transmitter and receiver systems; a receiver circuit section  4  and a transmitter circuit section  5  which are connected to the switch circuit  3 ; and a local oscillator  6  for generating a local signal required in the frequency conversion processing by the circuits  4  and  5 . 
   The receiver circuit section  4 , the transmitter circuit section  5  and the local oscillator  6  are mounted in the same semiconductor chip (not shown) in a semiconductor integrated circuit device  9 . Further, the semiconductor integrated circuit device  9  comprises a package frame (terminals  91  to  94 ), part of which protrudes outside the package. The package frame (terminals  91  to  94 ) is connected within the package to the receiver circuit section  4  or the transmitter circuit section  5  via bonding wire (not shown). The terminals  91  and  92  are terminals for connecting the receiver circuit section  4  to an external component (the switch circuit  3 ), and the terminals  93  and  94  are terminals for connecting the transmitter circuit section  5  to an external component (the switch circuit  3 ). 
   The switch circuit  3  selects either one of the receiver circuit section  4  and the transmitter circuit section  5  to render a state in which the circuit selected and the band pass filter  2  are connected. 
   The receiver circuit section  4  comprises a low noise amplifier  41  for amplifying the output signal of the switch circuit  3 ; an image rejection mixer  42  for generating an intermediate frequency signal by mixing the output signal of the low noise amplifier  41  and the local signal of the local oscillator  6 , and for removing an image signal from this intermediate frequency signal; a band pass filter  43  for limiting the output signal of the image rejection mixer  42  to within a predetermined frequency band; a limiter amplifier  44  for amplifying the output signal of the band pass filter  43 ; a demodulator  45  for carrying out demodulation processing on the output signal of the limiter amplifier  44 ; and a slicer  46  for waveform shaping the output signal of the demodulator  45  and then outputting this signal to an internal circuit (not shown). 
   On the other hand, the transmitter circuit section  5  comprises an I/Q quadrature modulator  51  for quadrature-modulating the local signal of the local oscillator  6  on the basis of an I signal, an I bar signal, a Q signal and a Q bar signal which are inputted by an internal circuit (not shown); and a variable gain power amplifier  52  for amplifying the output signal of the I/Q quadrature modulator  51  and then transmitting same to the switch circuit  3 . 
   As can be seen from  FIG. 3 , the antenna  1  and the band pass filter  2  are an unbalanced circuit, and the receiver circuit section  4  and the transmitter circuit section  5  are balanced circuits. A transformer circuit (referred to as a balun hereinafter) must be provided between the unbalanced circuit and the balanced circuits. Consequently, in the conventional high frequency signal transceiver apparatus shown in  FIG. 3 , a balun function is also added to the switch circuit  3 . 
   The balun must be provided with inductors having a large inductance value, and it is therefore big and difficult to install the balun in the semiconductor integrated circuit device. Consequently, the switch circuit  3  provided with the balun function is an external component rather than being installed in the semiconductor integrated circuit device  9 . With a conventional transceiver apparatus, when the transmitter and receiver circuit sections are balanced circuits, the balun is therefore made an external component, which has precluded miniaturization. 
   Furthermore, the conventional high frequency signal transceiver apparatus shown in  FIG. 3  is constituted such that the terminals which connect the receiver circuit section  4  to an external component, and the terminals which connect the transmitter circuit section  5  to an external component are not shared, meaning that the number of terminals provided in the semiconductor integrated circuit device  9  is high, which has made miniaturization impossible. 
   SUMMARY OF THE INVENTION 
   In view of the foregoing problems, it is an object of the present invention to provide a transceiver apparatus that permits miniaturization even when the antenna is an unbalanced circuit and the transmitter circuit section and the receiver circuit section are balanced circuits. 
   In order to achieve the above object, in case that the high frequency signals in or above the GHz band, inductor elements of bonding wire and package frame are utilized as the necessary inductance to high frequency signal transceiver apparatus. 
   The transceiver apparatus according to an embodiment of the present invention is constituted comprising: a semiconductor integrated circuit device that mounts on the same semiconductor chip a balanced receiver circuit for receiving a received signal as a differential input, a balanced transmitter circuit for outputting a transmitted signal as a differential output and that has two terminals connected to connecting nodes that connect the balanced receiver circuit and the balanced transmitter circuit; first and second capacitors connected to the terminals respectively; an external inductor connected to the first and second capacitors; an band pass filter and an antenna coupled to the first capacitor; and an third capacitor connected to the second capacitor. 
   A balun is consisted of inductor/capacitor elements, which the bonding wires and the package frame that is coupled via the bonding wires to the semiconductor chip have, capacitor elements, which metal layer patterns between said connecting nodes formed in the semiconductor chip and the bonding wires have, the external inductor, and said first, second and third capacitors. 
   By this construction, it is possible to reduce the number of terminals of the semiconductor integrated circuit device, and is no longer necessary to provide a big balun as an external component. As a result, it permits miniaturization of the transceiver apparatus. 
   Furthermore, from the point of view of facilitating impedance matching during transmission, a low noise amplifier for receiving a received signal from the balun as a differential input and which is provided in the balanced receiver circuit is desirably a cascode amplifier. 
   Furthermore, from the point of view of facilitating impedance matching during reception, a power amplifier for outputting a transmission signal to the balun as a differential output and which is provided in the balanced transmitter circuit is an amplifier whose power feed elements are desirably an inductor and a diode. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows the constitution of an embodiment of the high frequency signal transceiver apparatus according to the present invention; 
       FIG. 2  shows the constitution of the balun, the low noise amplifier, and the variable gain power amplifier of the high frequency signal transceiver apparatus of  FIG. 1 ; and 
       FIG. 3  shows the constitution of a conventional high frequency signal transceiver apparatus. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   A description will now be provided for an embodiment of the present invention, with reference to the drawings. The constitution of an embodiment of the high frequency signal transceiver apparatus according to the present invention is shown in  FIG. 1 . Further, the same reference symbols have been assigned to those components which are the same as those in  FIG. 3 , and a description thereof is therefore omitted here. 
   The receiver circuit section  4 , the transmitter circuit section  5  and the local oscillator  6  are mounted in the same semiconductor chip (not shown) in a semiconductor integrated circuit device  7 . Further, the semiconductor integrated circuit device  7  comprises a package frame (terminals  71  and  72 ), part of which protrudes outside the package. The package frame (terminals  71  and  72 ) is connected within the package to the receiver circuit section  4  and the transmitter circuit section  5  via bonding wire (not shown). The terminals  71  and  72  are terminals for connecting the receiver circuit section  4  and the transmitter circuit section  5  respectively to an external part of the balun (outer balun)  80 . 
   The constitution of the balun in the transceiver apparatus according to the present embodiment and the constitution of the low noise amplifier  41  and the variable gain power amplifier  52  are shown in  FIG. 2 . The same reference symbols have been assigned to those components which are the same as those in  FIG. 1 , and a description thereof is therefore omitted here. 
   First, the constitution of the balun  8  will be described. The balun  8  comprises capacitors C 1  to C 5  and inductors L 1  to L 5 . The capacitors C 1 ,C 2  and C 3  are external capacitor elements. The capacitor C 4  is a capacitor element formed by the package frame and bonding wires. The capacitor C 5  is a capacitor provided by the metal patterns in the semiconductor chip between the bonding wires and the connecting nodes that connects the low noise amplifier  41  and the variable gain power amplifier  52 . 
   The inductor L 1  is an external inductor element. The inductors L 2  and L 3  are inductor elements formed by the package frame. The inductors L 4  and L 5  are inductor elements formed by bonding wire. 
   The balun  8  is made of the internal part and the external part. 
   The external part of the balun comprises external capacitors C 1 , C 2  and C 3 , and an external inductor L 1 . 
   The internal part of the balun is formed by inductors, L 2 , L 3 , L 4  and L 5 , and capacitors C 4  and C 5 . The inductors, L 2 , L 3 , L 4  and L 5  and capacitor C 4  are what the package frame and bonding wires have in themselves. Therefore, there is no need to attach these inductors and capacitors as other necessary part. 
   In the high frequency signal transceiver apparatus according to the present embodiment, the inductance value of the bonding wire is substantially 2.2 nH, and the inductance value of the package frame is substantially 1 nH. There are barely any errors due to manufacturing variations in the inductance value of the bonding wire. 
   The band pass filter  2  is connected to the connecting node that connects the capacitor C 2  and the inductor L 1 . Further, the band pass filter  2  is connected to the connecting node that connects the capacitor C 6  in the low noise amplifier  41  and the capacitor C 8  in the variable gain power amplifier  52 , via the capacitor C 2 , the inductor L 2 , and the inductor L 4 . Further, the band pass filter  2  is connected, via the inductor L 1 , the capacitor C 3 , the inductor L 3 , and the inductor L 5 , to the connecting node that connects the capacitor C 7  in the low noise amplifier  41  and the capacitor C 9  in the variable gain power amplifier  52 . 
   The connecting node that connects the inductor L 1  and the capacitor C 3  is connected to ground via the capacitor Cl. Further, the connecting node that connects the inductor L 2  and the inductor L 4  is connected via the capacitor C 4  to the connecting node that connects the inductor L 3  and the inductor L 5 . In addition, the connecting node that connects the inductor L 4  and the capacitor C 6  in the low noise amplifier  41  (and the capacitor C 8  in the variable gain power amplifier  52 ) is connected via the capacitor C 5  to the connecting node that connects the inductor L 5  and the capacitor C 7  in the low noise amplifier  41  (and the capacitor C 9  in the variable gain power amplifier  52 ). 
   The balun  8  functions as a transformer circuit for the unbalanced circuit (the antenna  1  and the band pass filter  2 ) and the balanced circuits (the low noise amplifier  41  and the variable gain power amplifier  52 ), and regulates the input impedance of the low noise amplifier  41  and the output impedance of the variable gain power amplifier  52 . 
   Next, a description will be provided for the constitution of the low noise amplifier  41 . The low noise amplifier  41  is a balanced cascode amplifier. The connecting node that connects the inductor L 4  and the capacitor C 5  is connected to the base of an NPN-type transistor Q 1  via the capacitor C 6 , and the connecting node that connects the inductor L 5  and the capacitor C 5  is connected to the base of an NPN-type transistor Q 2  via the capacitor C 7 . A predetermined bias voltage V B2  is applied to the respective base of the transistors Q 1  and Q 2 . 
   The collector of the transistor Q 1  is connected to a terminal which supplies a fixed voltage V CC , via a resistor R 1  and an NPN-type transistor Q 3  which is cascode-connected to the transistor Q 1 . The collector of the transistor Q 2  is connected to the terminal supplying the fixed voltage V CC , via a resistor R 2  and an NPN-type transistor Q 4  which is cascode-connected to the transistor Q 2 . A predetermined bias voltage V B1  is applied to the respective base of the transistors Q 3  and Q 4 . 
   Also, the emitter of the transistor Q 1  is connected to ground via an impedance element Z 1  and the emitter of the transistor Q 2  is connected to ground via an impedance element Z 2 . Further, the connecting node that connects the transistor Q 3  and the resistor R 1 , and the connecting node that connects the transistor Q 4  and the resistor R 2  are connected to the image rejection mixer  42  (see  FIG. 1 ). 
   The high frequency signal transceiver apparatus according to the present embodiment stops feeding to the receiver circuit section  4  (see  FIG. 1 ) during transmission, thereby rendering the receiver circuit section  4  inoperable. The low noise amplifier  41  is a cascode amplifier, and therefore, during transmission, the resistor R 1  exerts no influence on the antenna  1  via the base-collector capacitance of the transistor Q 1 . As a result, the receiver circuit section  4  is rendered inoperable during transmission and the real part of the output impedance of the variable gain power amplifier  52  as seen by the antenna  1  is easily 50Ω. Therefore, impedance matching with the antenna  1  whose input impedance real part is 50Ω becomes straightforward. 
   A description will be provided next for the variable gain power amplifier  52 . The variable gain power amplifier  52  is a balanced amplifier constituted comprising a diode and an inductor as power feed elements. This inductor is formed by the spiral pattern of the metal layer in the semiconductor chip. The I/Q quadrature modulator  51  (see  FIG. 1 ) is connected to the respective base of NPN-type transistors Q 5  and Q 6 . The base of the transistor Q 5  is connected to an AC voltage source P 1  via a capacitor C 10 , and the base of the transistor Q 6  is connected to an AC voltage source P 2  via a capacitor C 11 . 
   The collector of the transistor Q 5  is connected to the cathode of a diode D 1 , and the collector of the transistor Q 6  is connected to the cathode of a diode D 2 . The anode of the diode D 1  is connected via an inductor L 6  to a terminal which supplies a control voltage V ctr . The anode of the diode D 2  is connected via an inductor L 7  to the terminal supplying the control voltage V ctr . 
   Further, the connecting node that connects the diode D 1  and the transistor Q 5  is connected to the connecting node that connects the inductor L 4  and the capacitor C 5 , via the capacitor C 8 , and the connecting node that connects the diode D 2  and the transistor Q 6  is connected to the connecting node that connects the inductor L 5  and the capacitor C 5 , via the capacitor C 9 . 
   The high frequency signal transceiver apparatus according to the present embodiment stops feeding to the transmitter circuit section  5  during reception, thereby rendering the transmitter circuit section  5  inoperable. In this embodiment, the variable gain power amplifier  52  is rendered as a balanced amplifier constituted comprising a diode and an inductor as power feed elements, and therefore, during reception, a resistance component in the variable gain power amplifier  52  exerts no influence on the antenna  1 . As a result, the transmitter circuit section  5  is rendered inoperable during reception and the real part of the input impedance of the low noise amplifier  41  is easily accomplished to be 50Ω. Therefore, impedance matching with the antenna  1  whose output impedance real part is 50Ω becomes straightforward. 
   Further, because the receiver circuit section  4  and the transmitter circuit section  5  are constituted as balance circuits, it is possible to use differentiation to cancel out internal digital noise and the like which is superposed on transmitted and received signals, thereby permitting an improvement in the accuracy of the transmitter and receiver operations. 
   Furthermore, a decrease in the frequency of the transmitted and received signals is accompanied by the need to enlarge the components which form the balun, which in turn makes miniaturization of the transceiver apparatus problematic. Therefore, the high frequency signals which are transmitted and received by the high frequency signal transceiver apparatus according to the present invention are desirably in or above the GHz band. In the description above, the inductors L 4  and L 5  were described only as bonding wire inductor elements but a similar balun can also be formed by wiring, using inductor elements produced by solder bump or another connection method, so as to obtain an appropriate inductor value. 
   In addition, the high frequency signal transceiver apparatus according to the present invention can be applied to a Bluetooth-adapted device such as a cellular phone, computer, or AV machine, for example.