Patent ID: 7474154

Claim:
A gain-boosted telescopic amplifier ( 100 ), comprising: first and second NMOS transistors (M P1 , M N1 ) forming an input pair for receiving a pair of differential input signals (V INP , V INN ), the first and second NMOS transistors having source terminals coupled to a tail current source ( 110 ); first and second NMOS cascode transistors (M P2 , M N2 ), each NMOS cascode transistor being coupled between a respective input pair transistor and a respective output node ( 102 , 104 ), each NMOS cascode transistor being configured in a gain-boosting feedback loop with an amplifier (AMP P1 , AMP N1 ) and being driven to a first bias voltage (V CSN ); first and second PMOS cascode transistors (M P3 , M N3 ) comprising a first, each PMOS cascode transistor being coupled between a respective output node ( 102 , 104 ) and a respective bias current source ( 106 , 108 ), each PMOS cascode transistor being configured in a gain-boosting feedback loop with an amplifier (AMP P2 , AMP N2 ) and being driven to a second bias voltage (V CSP ); a first clamping circuit coupled between the gate terminal of the first PMOS cascode transistor and a power supply voltage and being driven by the second bias voltage, the first clamping circuit limiting the gate voltage of the first PMOS cascode transistor to be within a threshold voltage of the second bias voltage; and a second clamping circuit coupled between the gate terminal of the second PMOS cascode transistor and a power supply voltage, the second clamping circuit limiting the gate voltage of the second PMOS cascode transistor to be within a threshold voltage of the second bias voltage, wherein the output nodes coupled to the pair of gain-boosted NMOS cascode transistors provides differential output voltages (V OUTN , V OUTP ).