INTEGRATED CIRCUIT COMPRISING A FREQUENCY DEPENDENT CIRCUIT, WIRELESS DEVICE AND METHOD OF ADJUSTING A FREQUENCY

• US 20160065131A1
• Filed: 01/27/2015
• Published: 03/03/2016
• Est. Priority Date: 08/27/2014
• Status: Active Grant

• Current Assignee: NXP USA, Inc. (NXP Semiconductors NV)
• Original Assignee: Freescale Semiconductor, Inc. (NXP Semiconductors NV)
• Inventors: PAVAO-MOREIRA, CRISTIAN, GOUMBALLA, BIRAMA, YIN, YI
• Granted Patent: US 9,407,199 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H03B 2200/005 including measures to switch a capacitor
• CPC Class Codes: H03B 5/1215 the current source or degeneration circuit being in common to both transistors of the pair, e.g. a cross-coupled long-tailed pair
• CPC Class Codes: H03B 5/1218 the generator being of the balanced type
• CPC Class Codes: H03B 5/1243 the means comprising voltage variable capacitance diodes
• CPC Class Codes: H03B 5/1265 switched capacitors
• CPC Class Codes: H03B 5/24 active element in amplifier being semiconductor device H03B5/26 takes precedence
• CPC Class Codes: H03J 2200/10 Tuning of a resonator by means of digitally controlled capacitor bank
• CPC Class Codes: H03L 7/18 using a frequency divider or counter in the loop H03L7/20, H03L7/22 take precedence

Abstract

An integrated circuit comprises a frequency dependent circuit comprising an input node, an output node and a main bank of selectable first capacitive elements that affect a frequency characteristic of the frequency dependent circuit. The frequency dependent circuit further comprises at least one shunt bank of selectable second capacitive elements located between ground and one of the input node or the output node, wherein at least one selectable second capacitive element switched out of the frequency dependent circuit is based on a number of the selectable first capacitive elements that are switched into the frequency dependent circuit.

Claims

1. An integrated circuit for a wireless device, the integrated circuit comprising a frequency dependent circuit comprising:

an input node;

an output node;

a main bank of selectable first capacitive elements that affect a frequency characteristic of the frequency dependent circuit,

at least one shunt bank of selectable second capacitive elements located between ground and one of the input node or the output node,

a controller operable to selectively enable or disable at least one selectable second capacitive element as a function of a number of the selectable first capacitive elements that are switched into the frequency dependent circuit.

2. The integrated circuit of claim 1, wherein the selectable second capacitive element(s) enabled or disabled are a function of a parasitic capacitance effect due to the number of the selectable first capacitive elements that are switched into the frequency dependent circuit.

3. The integrated circuit of claim 1, wherein the at least one shunt bank of selectable second capacitive elements comprises a first shunt bank of selectable second capacitive elements located between ground and the input node and a second shunt bank of selectable second capacitive elements located between ground and the output node.

4. The integrated circuit of claim 3, wherein the controller is arranged to switch out corresponding selectable second capacitive elements of the first shunt bank and second shunt bank of the frequency dependent circuit.

5. The integrated circuit of claim 4, wherein a capacitance value of a selected capacitive element from the first shunt bank of selectable second capacitive elements corresponds to a capacitance value of a selected second capacitive element from the second shunt bank of selectable second capacitive elements such that a combination of a total shunt capacitance of the first shunt bank of selectable second capacitive elements and second shunt bank of selectable second capacitive elements is substantially constant.

6. The integrated circuit of claim 1, wherein the controller is arranged to switch out at least one selectable second capacitive element to maintain a constant capacitance adjustment step independent of the number of the selectable first capacitive elements that are switched into the frequency dependent circuit.

7. The integrated circuit of claim 1, wherein the controller is operably coupled to the main bank of selectable first capacitive elements and configured to apply a first control signal to switch a number of the selectable first capacitive elements in or out of the frequency dependent circuit to affect the frequency characteristic of the frequency dependent circuit.

8. The integrated circuit of claim 1, wherein the controller is operably coupled to the at least one shunt bank of selectable second capacitive elements and configured to apply a second control signal to switch the selectable second capacitive elements in or out of the frequency dependent circuit.

9. The integrated circuit of claim 8, wherein the first control signal comprises a control word and the controller is operably coupled to both the main bank of selectable first capacitive elements and the at least one shunt bank of selectable second capacitive elements, wherein the second control signal is an inverted representation of the first control signal.

10. The integrated circuit of claim 1, wherein the at least one shunt bank of selectable second capacitive elements comprises at least one further capacitive element located in parallel to the shunt bank of selectable second capacitive elements.

11. The integrated circuit of claim 1, wherein at least one from a group of:

the main bank of selectable first capacitive elements, and the at least one shunt bank of selectable second capacitive elements, comprises binary weighted capacitive banks or thermometric controlled capacitive banks.

12. The integrated circuit of claim 1, wherein the main bank of selectable first capacitive elements comprises a bank of coarse-tuning capacitor elements in parallel with a bank of fine-tuning capacitor elements.

13. The integrated circuit of claim 12, wherein the at least one shunt bank of selectable second capacitive elements switched into or out of the frequency dependent circuit corresponds to at least one capacitive element of the bank of fine-tuning capacitor elements being switched out of or into the frequency dependent circuit.

14. The integrated circuit of claim 1, wherein at least one from a group of:

the main bank of selectable first capacitive elements, and the at least one shunt bank of selectable second capacitive elements, comprises a plurality of varactors.

15. The integrated circuit of claim 14, wherein the plurality of varactors are formed from at least one of:

bipolar junction transistor switched capacitances, metal oxide semiconductor based switched capacitances.

16. The integrated circuit of claim 1, wherein the frequency characteristic is a resonant frequency of the frequency dependent circuit.

17. The integrated circuit of claim 1, wherein the device is from a group of:

a long range radar device, short range radar device, operating at millimetre waveform frequencies.

18. A wireless device, comprising a frequency dependent circuit comprising:

an input node;

an output node;

a main bank of selectable first capacitive elements that affect a frequency characteristic of the frequency dependent circuit,

at least one shunt bank of selectable second capacitive elements located between ground and one of the input node or the output node,

a controller operable to selectively enable or disable at least one selectable second capacitive element as a function of a number of the selectable first capacitive elements that are switched into the frequency dependent circuit.

19. A method of adjusting a frequency characteristic of a wireless device comprising a frequency dependent circuit comprising an input node, an output node and a main bank of selectable first capacitive elements and at least one shunt bank of selectable second capacitive elements that affect a frequency characteristic of the frequency dependent circuit, wherein the method comprises:

switching into the frequency dependent circuit a number of the selectable first capacitive elements; and

selectively enabling or disabling at least one selectable second capacitive element as a function of the number of the selectable first capacitive elements switched into the frequency dependent circuit.

20. The method of claim 19 wherein the selectable second capacitive element(s) are selectively enabled or disabled as a function of a parasitic capacitance effect due to the number of the selectable first capacitive elements that are switched into the frequency dependent circuit.