Patent ID: 7567125

Claim:
An apparatus including a differential amplifier with multiple signal gains for amplifying a differential input signal over a wide dynamic range, comprising: differential input electrodes to convey a differential input signal; differential output electrodes to convey a differential output signal; first differential amplifier circuitry having a first signal gain and coupled between said differential input and output electrodes to receive at least a first portion of said differential input signal and provide a first portion of said differential output signal, and including a first differential amplifier sub-circuit to receive said at least said first portion of said differential input signal and a first tail current, and provide said first portion of said differential output signal in relation to said first signal gain, and a first bias sub-circuit coupled to said first differential amplifier sub-circuit to provide said first tail current; and second differential amplifier circuitry having a second signal gain lower than said first signal gain and coupled between said differential input and output electrodes to receive at least a second portion of said differential input signal and provide a second portion of said differential output signal, and including a second differential amplifier sub-circuit to receive said at least said second portion of said differential input signal and a second tail current, provide said second portion of said differential output signal in relation to said second signal gain, and a second bias sub-circuit coupled to said second differential amplifier sub-circuit to provide said second tail current; wherein, over a predetermined range of values of said differential input signal, a ratio of said differential output signal to said differential input signal varies in relation to a continuous combination of said first and second signal gains.