Patent ID: 6583667
Filing Date: 2003-06-24
Classification: H03F,H03G

Abstract:
A high frequency CMOS differential amplifier, comprising:a high frequency variable gain amplifier for providing a differential variable gain amplification of a first and a second input signal, where the gain of said high frequency variable gain amplifier depends on a first and a second bias current applied to said high frequency variable gain amplifier, said high frequency variable gain amplifier comprising at least two differential amplifiers; a temperature sensing circuit for providing a band-gap reference voltage plus proportional to absolute temperature (PTAT) dependent current generator, and a temperature independent first and second reference current; a gain-slope correction circuit for receiving a first and a second control voltage, said temperature independent first reference current and said temperature PTAT dependent current and producing an intermediate control voltage as a function of temperature by comparing said temperature independent first reference current and said PTAT dependent current, thereby compensating for a change in slope of the gain control characteristics with temperature of said high frequency variable gain amplifier; a gain compensation circuit for receiving said temperature independent second reference current, and a biasing current which is modified to correct the temperature/process dependency of said variable gain amplifier; and a bias control circuit for receiving said intermediate control voltage, said second control voltage, and said biasing current and producing said first and said second bias current by comparing said intermediate control voltage against reference voltages.