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

• US 7,019,598 B2
• Filed: 09/22/2003
• Issued: 03/28/2006
• Est. Priority Date: 11/12/1998
• Status: Expired due to Term

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Kwan, Tom W., Duncan, Ralph
• Primary Examiner(s): MIS, DAVID C
• Application Number:
  US10/665,631
• Publication Number:
  US 20050030108A1
• Time in Patent Office: 918 Days
• Field of Search: 331/8, 331/11, 331/14, 331/16, 331/17, 331/23, 331/25, 331/34, 331/36.C, 331/66, 331/117.R, 331/117.FE, 331/117.D, 331/175, 331/176, 331/177.V, 331/179, 331185-186
• US Class Current: 331/176
• 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

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 temperature.

2. The integrated VCO circuit of claim 1, wherein said adaptive bias circuit comprises:

a transconductance bias cell having an output that varies with temperature; and

an adaptive cell responsive to said output of said transconductance bias cell that provides a bias voltage to a gate of each of said pair of driver transistors.

3. The integrated VCO circuit of claim 2, wherein the adaptive cell has a biasing transistor having a gate coupled to said output of said transconductance bias cell, a source coupled to a reference power supply, and a drain coupled to said gates of said driver transistors;

and

wherein said biasing transistor is scaled to maintain a transconductance relationship characterized by g_mM1/M2=k(g_mM3);

wherein g_mM1/M2 is the transconductance of said pair of driver transistors, g_mM3 is the transconductance of said biasing transistor, and k is defined by the operating characteristics of said transconductance bias cell.

4. The integrated VCO circuit of claim 1, wherein said VCO and said adaptive bias circuit are disposed on a common substrate.

5. The integrated VCO circuit of claim 1, wherein said adaptive bias circuit causes a gate-to-source voltage (V_gs) of said driver transistors to move in response to temperature variations.

6. The integrated VCO circuit of claim 5, wherein said V_gs of said driver transistors are adjusted so to compensate for any transconductance variations that are caused by temperature variations of said VCO.

7. An integrated VCO circuit comprising:

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

means for maintaining a constant transconductance of said pair of driver transistors.

8. The integrated VCO circuit of claim 7, wherein said means for maintaining includes means for adjusting a gate-to-source voltage (V_gs) of said pair of driver transistors.

9. The integrated VCO circuit of claim 7, wherein said means for maintaining

includes:

means for determining a temperature variation of said VCO; and

means for adjusting a bias voltage of said pair of driver transistors based on said temperature variation, so as to maintain a constant transconductance of said pair of driver transistors.

10. The integrated VCO circuit of claim 7, wherein said means for maintaining includes:

means for adjusting a gate-to-source voltage of said pair of driver transistors based on said temperature variation, so as to maintain a constant transconductance of said pair of driver transistors.