Integrated VCO having an improved tuning range over process and temperature variations

• US 6,803,829 B2
• Filed: 06/17/2002
• Issued: 10/12/2004
• Est. Priority Date: 05/26/1999
• Status: Expired due to Term

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Duncan, Ralph, Kwan, Tom W.
• Primary Examiner(s): Mis, David C.
• Application Number:
  US10/171,762
• Publication Number:
  US 20030030497A1
• Time in Patent Office: 848 Days
• Field of Search: 331/11, 331/14, 331/16, 331/17, 331/25, 331/34, 331/36.C, 331/117.R, 331/117.FE, 331/176, 331/177.V, 331/179, 331/8, 331/23, 331/66, 331/185, 331/186
• US Class Current: 331/34
• CPC Class Codes: H01F 17/0006 Printed inductances printed coils for dynamo-electric machines H02K3/26; printed circuits H05K
• CPC Class Codes: H01F 17/0013 with stacked layers
• CPC Class Codes: H01F 2017/0053 with means to reduce eddy currents
• CPC Class Codes: H01F 2021/125 Printed variable inductor with taps, e.g. for VCO
• CPC Class Codes: H01L 23/5227 Inductive arrangements or effects of, or between, wiring layers other inductive arrangements H01L23/645
• CPC Class Codes: H01L 27/0248 for electrical or thermal protection, e.g. electrostatic discharge [ESD] protection
• CPC Class Codes: H01L 27/08 including only semiconductor components of a single kind
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 2924/09701 Low temperature co-fired ceramic [LTCC]
• CPC Class Codes: H01L 2924/3011 Impedance
• CPC Class Codes: H03B 2200/0038 including a current mirror
• CPC Class Codes: H03B 2201/025 the means being an electronic switch for switching in or out oscillator elements
• CPC Class Codes: H03B 2201/0266 the means comprising a transistor
• CPC Class Codes: H03B 5/1209 the amplifier having two current paths operating in a differential manner and a current source or degeneration circuit in common to both paths, e.g. a long-tailed pair. H03B5/1215 takes precedence
• CPC Class Codes: H03B 5/1212 the amplifier comprising a pair of transistors, wherein an output terminal of each being connected to an input terminal of the other, e.g. a cross coupled pair
• CPC Class Codes: H03B 5/1228 the amplifier comprising one or more field effect transistors
• CPC Class Codes: H03B 5/1253 the transistors being field-effect transistors
• CPC Class Codes: H03B 5/364 the amplifier comprising field effect transistors H03B5/366 takes precedence
• CPC Class Codes: H03D 7/161 all the frequency changers being connected in cascade
• CPC Class Codes: H03D 7/18 : Modifications of frequency-changers for eliminating image frequencies H03D7/16 takes precedence
• CPC Class Codes: H03G 1/0029 : using FETs
• CPC Class Codes: H03H 11/1291 : Current or voltage controlled filters
• CPC Class Codes: H03J 1/0075 : where the receiving frequencies of the stations are stored in a permanent memory, e.g. ROM
• CPC Class Codes: H03J 2200/10 : Tuning of a resonator by means of digitally controlled capacitor bank
• CPC Class Codes: H03J 3/04 : Arrangements for compensating for variations of physical values, e.g. temperature
• CPC Class Codes: H03J 3/08 : by varying a second parameter simultaneously with the tuning, e.g. coupling bandpass filter
• CPC Class Codes: H03J 3/185 : with varactors, i.e. voltage variable reactive diodes
• CPC Class Codes: H03L 1/023 : by using voltage variable capacitance diodes
• CPC Class Codes: H03L 7/10 : for assuring initial synchronisation or for broadening the capture range
• CPC Class Codes: H03L 7/23 : with pulse counters or frequency dividers

Abstract

An integrated VCO having an improved tuning range over process and temperature variations. There is therefore provided in a present embodiment of the invention an integrated VCO. The VCO comprises, a substrate, a VCO tuning control circuit responsive to a VCO state variable that is disposed upon the substrate, and a VCO disposed upon the substrate, having a tuning control voltage input falling within a VCO tuning range for adjusting a VCO frequency output, and having its tuning range adjusted by the tuning control circuit in response to the VCO state variable.

Claims

1. An integrated VCO circuit comprising:

a VCO having a pair of driver transistors and a tank circuit; and

a tuning control circuit producing a sliding voltage window coupled to said tank circuit for adjusting the frequency range of the VCO, said sliding voltage window having a fixed voltage magnitude with a sliding center voltage that is responsive to temperature so as to compensate for temperature change in said pair of driver transistors.

2. The integrated VCO circuit of claim 1, wherein said tuning control circuit comprises:

a resistive divider circuit providing said sliding voltage window;

a first comparator having a positive input coupled to a state signal and a negative input coupled to a first reference voltage of said sliding voltage window;

a second comparator having a positive input coupled to said state signal, and a negative input coupled to a second reference voltage of said sliding voltage window;

wherein outputs of said first and second comparator control said tank circuit and thereby a resonant frequency of said VCO;

a bias transistor responsive to temperature and coupled to said resistive divider circuit at a tap point between said first and second reference voltages, wherein said bias transistor adjusts said sliding center voltage of said sliding voltage window responsive to temperature so as to compensate for a gate-to-source voltage change with temperature in said pair of driver transistors.

3. An integrated VCO circuit comprising:

a VCO having a pair of driver transistors and a tank circuit;

an adaptive bias circuit coupled to said driver transistors that maintains a nearly constant transconductance in said pair of driver transistors in response to changing circuit temperature; and

a tuning control circuit coupled to said tank circuit that has a window of control voltages, said window having fixed voltage magnitude with a sliding center voltage that is responsive to temperature;

wherein maintaining a constant transconductance in said driver transistors assists in maintaining said sliding center voltage of said window of control voltages.

4. The integrated VCO circuit of claim 3, wherein said VCO, said adaptive bias circuit, and said tuning control circuit are disposed on a common substrate.

5. A method for minimizing non-linear effects of temperature variation in an integrated VCO having a tuning control circuit with a sliding voltage window, and a pair of driver transistors, the method comprising:

sensing ambient circuit temperature;

varying a gate-to-source voltage of each of the pair of driver transistors in response to the ambient circuit temperature to maintain nearly constant transconductance in the pair of driver transistors; and

adjusting the sliding voltage window in response to said varying gate-to-source voltage of each of the pair of driver transistors.

6. An integrated VCO circuit comprising:

a pair of driver transistors;

a tank circuit coupled to said pair of driver transistors;

a tuning control circuit having a sliding voltage control window coupled to said tank circuit for setting a frequency tuning range;

a means for maintaining a constant transconductance in said driver transistors over varying temperature conditions; and

a means for adjusting a center voltage for said sliding voltage control window over varying temperature conditions.

7. The integrated VCO circuit of claim 6, wherein said a pair of driver transistors, said tank circuit, said tuning control circuit, said means for maintaining a constant transconductance in said driver transistors, and said means for adjusting a center voltage for said sliding voltage control window are disposed on a common substrate.