Patent ID: 6127890
Filing Date: 2000-10-03
Classification: H03F,H03G

Abstract:
A variable gain circuit for amplifying an input signal with a gain which depends on a control voltage, the variable gain circuit comprising:a first amplifier receiving an input signal and the control voltage and amplifying the input signal with a gain which depends on the control voltage to produce a first amplified signal, the gain of the first amplifier being substantially proportional to the control voltage in a relatively low region of the control voltage; anda second amplifier connected to the first amplifier and receiving the first amplified signal and the control voltage and amplifying the first amplified signal with a gain which depends on the control voltage, the gain of the second amplifier being substantially proportional to the control voltage in a relatively high region of the control voltage, the second amplifier including a gain clamp circuit which maintains the gain of the second amplifier constant in a relatively low region of the control voltage.