Browse Prior Art Database

Delay Element for High Speed Ring Oscillator

IP.com Disclosure Number: IPCOM000113770D
Original Publication Date: 1994-Oct-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 55K

Publishing Venue

IBM

Related People

Emeigh, R: AUTHOR [+4]

Abstract

A temperature compensated delay element for ring oscillators is disclosed. The circuit features sub-3.6 volt power supply, high frequency operation, low current requirements, and no external components.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 85% of the total text.

Delay Element for High Speed Ring Oscillator

      A temperature compensated delay element for ring oscillators is
disclosed.  The circuit features sub-3.6 volt power supply, high
frequency operation, low current requirements, and no external
components.

      The single stage delay element is shown in the Figure.  When
the differential signal A0-A1 goes high, Q3 turns on pulling NET3
low.  Q1 turns on, discharging 21 until it falls a base-emitter
voltage (vbe) below NET3 and Q5 turns on.  Additionally, Q2 and Q10
turn off and R11 pulls NET7 up to P5VVCO while the low impedance of
Q4 (as opposed to R11) drives the next delay element as well as the
capacitor C0 and any parasitics.  Since R11 only drives a base and
the collector of a turned off NPN, it can be fairly large, reducing
power.  Since the circuit is fully differential it's operation is
symmetric.

      A standard differential voltage to current (V-I) converter is
used to decrease or increase the current at pin G1 as the current is
increased or decreased at pin G0.  As the current at G0 increases,
the vbe of Q4 and Q5 increase.  As this is happening, the current at
G1 is decreasing, raising the voltage at the base of Q12 which causes
Q11 to conduct less current, which lowers the voltage drop on R11 and
R12 and compensates for the increased vbe of Q4 and Q5.  The diode
string formed by Q13 and Q14 are biased by a DC current which is
one-half the range of current expected at pin G1.  By varying...