# US 8,786,338 B2 · Delay locked loop

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- Number: US 8,786,338 B2
- Document ID: US8786338B2
- Status: Granted
- Kind: B2
- Application number: 13/295,885
- Filed: 2011-11-14
- Published: 2013-05-16
- Granted: 2014-07-22
- Earliest claimed: 2011-11-14
- Assignees: Texas Instruments Incorporated
- Applicants: Vijay B. Rentala; Srinath M. Ramaswamy; Brian P. Ginsburg; Eunyoung Seok; Baher S. Haroun
- Inventors: Vijay B. Rentala; Srinath M. Ramaswamy; Brian P. Ginsburg; Eunyoung Seok; Baher S. Haroun
- Web page: https://patentgrep.com/patent/US8786338B2

## CPC

- H03L 7/0812: {and where no voltage or current controlled oscillator is used}
- G01S 13/00: Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S 13/08: Systems for measuring distance only (indirect measurement G01S13/46)
- H03L 7/0891: {the up-down pulses controlling source and sink current generators, e.g. a charge pump}
- H03K 2005/00071: {by adding capacitance as a load}
- H03L: AUTOMATIC CONTROL, STARTING, SYNCHRONISATION OR STABILISATION OF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES (generation of oscillations H03B)
- G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- H03K: PULSE TECHNIQUE (measuring pulse characteristics G01R; modulating sinusoidal oscillations with pulses H03C; transmission of digital information H04L; discriminator circuits detecting phase difference between two signals by counting or integrating cycles of oscillation H03D3/04; automatic control, starting, synchronisation or stabilisation of generators of electronic oscillations or pulses where the type of generator is irrelevant or unspecified H03L; coding, decoding or code conversion, in general H03M)

## Abstract

A method for providing a plurality of narrow pulses is provided. A first pulse having a first width is received by a delay line having a plurality of delay cells. This first pulse has a first width. In response to this first pulse, a plurality of second pulses is generated by the delay line, where each second pulse has a second width that is less than the first width. First and second delay pulses are also generated by the delay line, and a delay for each delay cell in the delay line can then be adjusted if a rising edge of the second delay pulse is misaligned with a falling edge of the first delay pulse.

## Claims

### Claim 1

An apparatus comprising:
a delay line having an input terminal, a control input terminal, a first control output terminal, a second control output terminal, and a plurality of taps, wherein the delay line is configured to receive a first pulse having a first width at its input terminal, and wherein the delay line is configured to output a first delayed pulse through the first control output terminal, and wherein the delay line is configured to output a second delayed pulse through the second control output terminal, and wherein each tap is configured to output a second pulse having a second width in response to the first pulse, and wherein the first width is greater than the second width;
a phase/frequency detector (PFD) that is coupled the first control output terminal and the second control output terminal so as to receive the first and second delayed pulses;
a charge pump that is coupled to the PFD; and
a filter that is coupled to the charge pump and the control terminal of the delay line.

### Claim 2 (depends on 1)

The apparatus of claim 1, wherein the delay line further comprises:
a plurality of delay cells that are coupled in series with one another in a sequence and that are each coupled to the control terminal, wherein the first delay cell of the sequence is coupled to the PFD, and wherein the last delay cell of the sequence is coupled to the PFD; and
a plurality of logic gates, wherein each logic gate is coupled across at least one of the delay cells, and wherein an output terminal of each gate forms at least one of the taps.

### Claim 3 (depends on 2)

The apparatus of claim 2, wherein each delay cell further comprises:
an inverter having an input terminal and an output terminal; and
a variable capacitor that is coupled to the output terminal of the inverter, wherein the variable capacitor is controlled by an output of the filter.

### Claim 4 (depends on 3)

The apparatus of claim 3, wherein the variable capacitor further comprises a varactor.

### Claim 5 (depends on 4)

The apparatus of claim 4, wherein each logic gate further comprises an AND gate.

### Claim 6 (depends on 5)

The apparatus of claim 5, wherein the plurality of second pulses span the first pulse.

### Claim 7

A method comprising:
receiving a first pulse having a first width by a delay line, and wherein the delay line includes a plurality of delay cells;
generating a plurality of second pulses by the delay line in response to the first pulse, wherein each second pulse has a second width, and wherein the first width is greater than the second width;
generating first and second delay pulses by the delay line; and
adjusting a delay for each delay cell in the delay line if a rising edge of the second delay pulse is misaligned with a falling edge of the first delay pulse.

### Claim 8 (depends on 7)

The method of claim 7, wherein the delay cells are coupled in series with one another in a sequence, and wherein the step of generating the first and second delay pulses by the delay line further comprises:
outputting the first delay pulse from the first delay cell of the sequence; and
outputting the second delay pulse from the last delay cell of the sequence.

### Claim 9 (depends on 8)

The method of claim 8, wherein the step of adjusting further comprises:
comparing the rising edge of the second delay pulse to see if it is misaligned with the falling edge of the first delay pulse;
generating first and second charge pump control signals to compensate for misalignment of the rising edge of the second delay pulse and the falling edge of the first delay pulse;
generate a control voltage in response to the first and second charge pump control signals; and
applying the control voltage to each delay cell.

### Claim 10 (depends on 9)

The method of claim 9, wherein the step of generating the plurality of second pulses further comprises logically combining outputs from a set of the delay cells to generate the plurality of second pulses.

### Claim 11 (depends on 9)

The method of claim 9, wherein the step of logically combining further comprises combining the input and output for each of the second delay cell of the sequence to the last delay cell of the sequence with one of a plurality of logic gates.

### Claim 12 (depends on 11)

The method of claim 11, wherein each logic gate is an AND gate.

### Claim 13

An apparatus comprising:
radar circuitry that is configured to transmit and receive terahertz radiation; and
a baseband circuit that is coupled to the radar circuitry so as to digitize a baseband signal, wherein the baseband circuitry includes:
a in-phase (I) channel;
a quadrature (Q) channel; and
a clock circuit having a clock generator and a delay locked loop (DLL), wherein the DLL includes:
a delay line having an input terminal, a control input terminal, a first control output terminal, a second control output terminal, and a plurality of taps, wherein the delay line is configured to receive a first pulse having a first width at its input terminal from the radar circuitry, and wherein the delay line is configured to output a first delayed pulse through the first control output terminal, and wherein the delay line is configured to output a second delayed pulse through the second control output terminal, and wherein each tap is coupled to the I and Q channels so as to output a second pulse having a second width in response to the first pulse, and wherein the first width is greater than the second width;
a PFD that is coupled the first control output terminal and the second control output terminal so as to receive the first and second delayed pulses;
a charge pump that is coupled to the PFD; and
a filter that is coupled to the charge pump and the control terminal of the delay line.

### Claim 14 (depends on 13)

The apparatus of claim 13, wherein the delay line further comprises:
a plurality of delay cells that are coupled in series with one another in a sequence and that are each coupled to the control terminal, wherein the first delay cell of the sequence is coupled to the PFD, and wherein the last delay cell of the sequence is coupled to the PFD; and
a plurality of logic gates, wherein each logic gate is coupled across at least one of the delay cells, and wherein an output terminal of each gate forms at least one of the taps.

### Claim 15 (depends on 14)

The apparatus of claim 14, wherein each delay cell further comprises:
an inverter having an input terminal and an output terminal; and
a variable capacitor that is coupled to the output terminal of the inverter, wherein the variable capacitor is controlled by an output of the filter.

### Claim 16 (depends on 15)

The apparatus of claim 15, wherein the variable capacitor further comprises a varactor.

### Claim 17 (depends on 16)

The apparatus of claim 16, wherein each logic gate further comprises an AND gate.

### Claim 18 (depends on 17)

The apparatus of claim 17, wherein a plurality of second pulses span the first pulse.

### Claim 19 (depends on 18)

The apparatus of claim 18, wherein the radar circuitry further comprises:
a phased array having a plurality of transceivers;
a controller that is coupled to each transceiver;
a distribution network that is coupled to each transceiver;
a local oscillator that is coupled to the distribution network; and
a pulse generator that is coupled to the local oscillator and to the input terminal of the delay line.

### Claim 20 (depends on 19)

The apparatus of claim 19, wherein the baseband circuit further comprises summing circuitry that is coupled to each transceiver, the I channel, and the Q channel.