Patent ID: 6781461
Filing Date: 2004-08-24
Classification: H03F,H03G

Abstract:
An apparatus for providing a drive signal for an amplification circuit configured to operate based upon a received differential control signal, the apparatus comprising:means for generating a signal including: a first circuit portion configured to receive a supply voltage signal and including a first differential transistor pair, the first differential transistor pair including (i) inverting and non-inverting differential input ports configured to receive a differential input signal and (ii) first and second pairs of differential output ports configured to respectively produce first and second differential output signals, the first and second differential output signals being responsive to the differential input signal and the supply voltage signal, the first differential output signal having a first voltage magnitude and the second differential output signal having a second voltage magnitude, wherein the first and second voltage magnitudes are offset from one another; and a second circuit portion including second and third differential transistor pairs, each second and third differential pair (i) being configured to receive the supply voltage signal and (ii) having first and second differential input ports; wherein the first differential input port of the second differential pair and the second differential input part of the second differential pair are configured to receive the first differential output signal, and the second differential input port of the third differential pair and the first differential input port of the third differential pair is configured to receive the second differential output signal; and wherein the second circuit portion produces a differential amplifier drive signal responsive to the received first and second differential output signals and to the supply voltage signal; means for receiving the supply voltage signal; means for receiving the differential input signal; means for producing the differential amplifier drive signal in response to the received supply voltage signal, the received differential input signal, and the received differential control signal; and means for adjusting the received differential input signal to a value where magnitudes of negative and positive components of the differential control signal (i) become equal to one another and (ii) are within a predetermined amount of a magnitude of the supply voltage signal.