Sampling Phase Detector Modules
Rev. V1
MSPDxxxx-x Series
1
1
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Features
Phase Locking to 22 GHz
Phase Locks DRO’s and VCO’s
Fully Integrated Module
Broadband Capability
Description
The sampling phase detector (SPD) module is a
hybrid circuit providing a fast step recovery diode,
coupling capacitors and a low barrier Schottky pair.
The Schottky pair is used as a sampling circuit
turned on by the fast step from the step recovery
diode (SRD), or in the frequency domain, the
Schottky acts as a mixer to mix the harmonic of the
SRD step closest to the microwave frequency. The
output is a beat frequency (the difference between
the harmonic of the reference and the microwave
frequency) and is just a DC voltage at the lock point.
It is used to phase lock DRO’s and VCO’s from 10 to
1000 MHz typical reference frequencies.
* Restrictions on Hazardous Substances, European Union Directive 2011/65/EU.
Functional Schematic & Pinouts
Part #1 Cap.
Microwave Frequency Step Recovery Diode Schottky Sampling Diodes
Power Drive Range FREF PREF CT6 TL TT CT0 VF @ 1 mA RDS
Max. Min. Range Typ. Typ.
pF dBm GHz MHz dBm pF ns ps pF mV Ω
MSPD1000-x 18 - 22 7 0.5 10 17 - 27 1.10 35 65 0.40 250 7
MSPD1002-x 3.0 - 4.1 7 2.5 25 17 - 27 0.76 20 50 0.36 250 8
MSPD1012-x 2.0 - 3.1 6 12.5 50 17 - 27 0.85 10 35 0.32 250 9
MSPD2018-x 0.45 - 0.70 4 22.0 100 17 - 23 0.50 6 45 0.23 425 16
Electrical Specification: TA = +25°C
1. Parts available in surface mount packages E50, E50SM, and H50. When ordering add the dash variant to the part number.
Sampling Phase Detector Modules
Rev. V1
MSPDxxxx-x Series
2
2
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2
Absolute Maximum Ratings
Parameter Absolute Maximum
Operating Temperature -65°C to +150°C
Storage Temperature -65°C to +150°C
Soldering Temperature +230°C for 5 seconds
Handling Procedures
Please observe the following precautions to avoid
damage:
Static Sensitivity
These electronic devices are sensitive to
electrostatic discharge (ESD) and can be damaged
by static electricity. Proper ESD control techniques
should be used when handling these devices.
Typical Performance (MSPD1012-E50) Recommended Circuit
A Typical Circuit Application
2. All circuits have broadband capability and are not limited to the frequencies stated.
Sampling Phase Detector Modules
Rev. V1
MSPDxxxx-x Series
3
3
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For further information and support please visit:
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Applications
The Sampling Phase Detector (SPD) is composed of
a comb generator, a coupling network and a single
balanced mixer. It is designed to be used in phase
locking circuits for microwave oscillators.
The following description of the operation of the SPD
refers to Fig. 1. The step recovery diode (SRD) D1
charges during the forward bias part of the AC cycle.
The charge is withdrawn during the reverse bias part
of the AC cycle, and D1 transitions, producing an
edge. The capacitors C1 and C2 differentiate the
edge into an impulse and apply this impulse to the
schottky diodes D2 and D3, which are turned on
briefly and apply a sample of the microwave signal
to the IF filter. When the reference signal and the
microwave signal are harmonically related, the same
voltage point on the microwave signal is applied to
the IF filter, producing a steady DC output or offset
voltage. When the two signals are not exactly
related, a different point on the microwave signal is
applied to the IF filter each cycle, producing a sine
wave with a frequency that is equal to the difference
between the microwave signal’s frequency and the
frequency of the closest harmonic of the reference
signal. This frequency is also defined as the
difference frequency.
The design criteria for the circuit, shown in Fig. 2, is
described below. Transformer T1 matches the
reference oscillator to the SRD and converts the
oscillator’s signal from single ended to balanced.
The SPD requires 17 dBm to 27 dBm from the
reference oscillator to work properly. The SRD
impedance, which is about 50 ohms at 17 dBm,
decreases as the drive level is increased. R1 and
R2, each of which should be about 50 ohms, provide
a termination for the microwave signal and dampen
reflections in the SPD caused by mismatches. C1
isolates the IF signal from the microwave source. Its
value should be chosen so it has a high impedance
(at least 150 ohms) at the IF frequency and a low
impedance (<10 ohms) at the microwave frequency.
Fig.1
Fig.2
C1 can be replaced by a high pass or band pass
filter network. The circuit’s performance can be
improved by matching the microwave source to the
Schottky diodes. Also use microwave layout rules for
the physical layout of the interface circuit between
the microwave source and the Schottky. R3 and C2
create a low pass filter which separates out the IF
signal. The cut off frequency of this filter should be
selected to block the next higher harmonic of the
reference oscillator. For example, the harmonics of a
100 MHz reference occur every 100 MHz, the cut off
frequency must be less then 100 MHz. R3 may be
replaced by an inductor of an appropriate value.
Care must be taken not to shunt the microwave
signal away from the Schottky with a low quality
inductor. R4, R5 and R6 provide the return path for
the IF signal. R4 provides a DC offset adjustment.
R5 and R6 should have a value of at least 100 ohms
and be placed as close to the SPD as possible. R5
and R6 keep the impulse and microwave signal
inside the SPD. Fig. 3 shows an alternative IF return
network with R4 removed. The resistors R5 and R6
can be replaced with low pass filters. The low pass
filters need to present a high impedance (Z >200 Ω)
to the SPD to keep from loading down the impulse
and microwave signal.
Fig.3
Sampling Phase Detector Modules
Rev. V1
MSPDxxxx-x Series
4
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There are four models of the SPD, each one is
designed to work at a particular microwave
frequency. This maximum frequency is not a cut off
frequency; but, it is a suggested upper limit based
on the Schottky junction capacitance. For the
MSPD0002 and MSPD1000, the transition time of
the SRD will limit the upper frequency to 4 GHz. The
circuit in Fig. 2 is designed to work with a sine wave
driving the SRD. The SRD can be driven with a
square wave or a pulse. For low frequency
(<20 MHz) references, a pulse drive will work better
then sine wave drive. The minimum requirements is
a forward bias cycle of at least 10 ns and a reverse
bias cycle long enough to remove all the stored
charge and allow the SRD to transition. The reverse
bias cycle should have a fall time less then 0.8 ns.
The maximum current in either direction should be
10 mA and the maximum reverse voltage should be
13 V. The greater the reverse voltage, the greater
the impulse generated. One way to achieve pulse
drive is shown in Fig. 4. The circuit uses a constant
current source to supply the forward bias. Then a
pulse is superimposed to reverse bias the SRD. R is
a minimum of 1000 ohms and C is 0.02 µF. The
forward voltage drop of the SRD is about 1 V and
varies about -2 mV/°C.
One property of the SPD is that the conversion
efficiency varies approximately as sin (npx) / (npx).
This is due to the impulse driving the Schottky.
Minimum conversion efficiency occurs when (npx) =
N where n and N are integers. The value of X is
controlled by the reference frequency and the value
of the coupling capacitors. When testing a new
design, adjusting the microwave frequency is
recommended to insure the circuit is not at a
minimum. If the circuit is at a minimum and the
reference frequency cannot be changed, the
coupling capacitance can be raised by adding
external capacitors.
There are several ways to connect a single balanced
mixer. The circuit in Fig. 2 is based on the circuit
shown in Fig. 5. Fig. 6 shows another possibility.
When used as a sampling mixer, the SPD has a
high conversion loss (example: Fref = 100 MHz,
Fmicrowave = 1 GHz and FIF = 1 KHz, Conversion
Loss = 25 dB).
Fig. 7 shows how IF output varies with microwave
power at various reference drive levels. For each
reference drive level there is an optimum microwave
input level. Excessive microwave input increases
phase noise, temperature drift and decreases IF
output.
When checking the diodes in the SPD with a
multimeter, be sure the voltage is limited to 2 V
maximum. While the SPD can be soldered into a
circuit by hand, limit the time that each lead is
heated to 5 seconds. Also, observe antistatic
precautions.
Fig.4
Fig.5
Fig.6
Fig.7
Sampling Phase Detector Modules
Rev. V1
MSPDxxxx-x Series
5
5
MACOM Technology Solutions Inc. (MACOM) and its affiliates reserve the right to make changes to the product(s) or information contained herein without notice.
Visit www.macom.com for additional data sheets and product information.
For further information and support please visit:
https://www.macom.com/support
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Sampling Phase Detector Modules
Rev. V1
MSPDxxxx-x Series
6
6
MACOM Technology Solutions Inc. (MACOM) and its affiliates reserve the right to make changes to the product(s) or information contained herein without notice.
Visit www.macom.com for additional data sheets and product information.
For further information and support please visit:
https://www.macom.com/support
6
Outline Drawing (E50)
Sampling Phase Detector Modules
Rev. V1
MSPDxxxx-x Series
7
7
MACOM Technology Solutions Inc. (MACOM) and its affiliates reserve the right to make changes to the product(s) or information contained herein without notice.
Visit www.macom.com for additional data sheets and product information.
For further information and support please visit:
https://www.macom.com/support
7
Outline Drawing (E50SM)
Sampling Phase Detector Modules
Rev. V1
MSPDxxxx-x Series
8
8
MACOM Technology Solutions Inc. (MACOM) and its affiliates reserve the right to make changes to the product(s) or information contained herein without notice.
Visit www.macom.com for additional data sheets and product information.
For further information and support please visit:
https://www.macom.com/support
8
Outline Drawing (H50)
Sampling Phase Detector Modules
Rev. V1
MSPDxxxx-x Series
9
9
MACOM Technology Solutions Inc. (MACOM) and its affiliates reserve the right to make changes to the product(s) or information contained herein without notice.
Visit www.macom.com for additional data sheets and product information.
For further information and support please visit:
https://www.macom.com/support
9
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