Back to results
US 6,169,459 AGranted
Active-bridge oscillator
AssigneeSandia Corporation
InventorKurt O. Wessendorf
Life of this patent
Estimating the term…
Abstract
An active bridge oscillator is formed from a differential amplifier where positive feedback is a function of the impedance of one of the gain elements and a relatively low value common emitter resistance. This use of the nonlinear transistor parameter h stabilizes the output and eliminates the need for ALC circuits common to other bridge oscillators.
Claims12
An active bridge oscillator comprising:
- a differential amplifier having an inverting input on a first gain device and a noninverting input on a second gain device, said devices each having a transconductance gm and inverting and noninverting outputs, said non-inverting outputs being connected as a coupled pair;
- a signal conditioning circuit connecting the inverting output of said first gain device to the noninverting input;
- a negative feedback path comprising a feedback resistance connected between said inverting and noninverting inputs, and a resonant circuit having a series resistance connected from said inverting input to ac ground;
- a positive feedback path consisting of the intrinsic resistance 1/gm of the gain devices and a relatively low ac resistance connected between said coupled pair and ac ground, the magnitude of said resistance being on the order of the sum of 1/gm of both gain devices.
1 more element
An active bridge oscillator comprising:
- a differential amplifier having an inverting input on a first gain device and a noninverting input on a second gain device, said devices each having a transconductance gm and inverting and noninverting outputs, said non-inverting outputs being connected as a coupled pair;
- a signal conditioning circuit connecting the inverting output of said first gain device to the noninverting input;
- a negative feedback path comprising a feedback resistance Rf connected between said inverting and noninverting inputs, and a resonant circuit having a series resistance Rm connected from said inverting input to ac ground, wherein said negative feedback ratio βn is a function of Rf and Rm;
- a positive feedback path consisting of the intrinsic resistance, 1/gm, of the gain devices and an ac resistance Re having a magnitude on the order of the sum of 1/gm of both gain devices connected between said coupled pair and ac ground, wherein said positive feedback ratio βp is a function of Re and 1/gm, and βn<βp<1.
1 more element
Dependencies are inferred from the claim text.