Radio frequency feedback amplifier circuits
First Claim
1. A radio frequency feedback amplifier circuit of high linearity at, and close to, the frequency of the input signal with which the circuit is to be used, the circuit comprising high gain amplifier means incorporating a bandpass filter in the form of a high Q resonance means (62) connected in the forward path of the amplifier means and having its resonant frequency at substantially the input frequency, and feedback means in the form of a linear passive circuit.
0 Assignments
0 Petitions
Accused Products
Abstract
A radio frequency feedback amplifier circuit of high linearity within the range of frequencies with which the circuit is to be used includes a high gain amplifier incorporating a bandpass filter in the form of a single resonator which may be tunable, connected in the forward path of the amplifier stage and tuned so that its resonant frequency is at substantially the signal frequency, and a linear passive feedback circuit. A tuning arrangement (64, 65, 66, 67) includes phase detection elements (66), such as a Gilbert cell, for determining the phase shift across the resonator (62) and for adjusting a variable capacitance (64, 65) within the resonator (62) to tune the resonant circuit, in dependence on the frequency of the input to the circuit. Such an amplifier circuit may be used to achieve high linearity and stability at reasonable manufacturing cost, with much greater simplicity than can be achieved using other feedback techniques.
35 Citations
29 Claims
- 1. A radio frequency feedback amplifier circuit of high linearity at, and close to, the frequency of the input signal with which the circuit is to be used, the circuit comprising high gain amplifier means incorporating a bandpass filter in the form of a high Q resonance means (62) connected in the forward path of the amplifier means and having its resonant frequency at substantially the input frequency, and feedback means in the form of a linear passive circuit.
Specification