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Precision Phase Shifter

IP.com Disclosure Number: IPCOM000051770D
Original Publication Date: 1981-Mar-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 2 page(s) / 29K

Publishing Venue

IBM

Related People

Ballatore, D: AUTHOR

Abstract

This article describes a phase shifter which can shift the phase of the output signal over a range of almost 360 degrees with respect to a squared input signal. Precision of the phase shift value depends only on that of a couple of resistors.

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Precision Phase Shifter

This article describes a phase shifter which can shift the phase of the output signal over a range of almost 360 degrees with respect to a squared input signal. Precision of the phase shift value depends only on that of a couple of resistors.

The input signal is fed to a phase frequency detector (PFD) where the input signal is compared with the feedback output signal from a voltage-controlled oscillator (VCO), and which provides a logical error signal, e, whose average value e is proportional to the phase and/or frequency difference between the input signal and the output feedback signal. The output of the PFD is supplied to an operational amplifier filter, the output of which is applied to the VCO.

If R1= infinity or E=0, the circuit of the figure operates as a conventional phase-locked loop, and the phase, phi out, of the output signal is equal to the phase, phi in, of the input signal.

If E is other than zero, resistor R1 Provides a current equal to E/R1 to the inverting input of the operational amplifier and the PFD provides through R0 a current equal to: ## (page 4514 equations (1) to (6))

Relation (6) shows that the phase shift has a constant value and that the precision of that value depends only on the precision of resistors R0 and R1.

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