SA612A
Double-balanced mixer and oscillator
Rev. 3 — 4 June 2014
Product data sheet
1. General description
The SA612A is a low-power VHF monolithic double-balanced mixer with on-board
oscillator and voltage regulator. It is intended for low cost, low-power communication
systems with signal frequencies to 500 MHz and local oscillator frequencies as high as
200 MHz. The mixer is a ‘Gilbert cell’ multiplier configuration that provides gain of 14 dB or
more at 45 MHz.
The oscillator can be configured for a crystal, a tuned tank operation, or as a buffer for an
external LO. Noise figure at 45 MHz is typically below 6 dB and makes the device
well-suited for high-performance cordless phone/cellular radio. The low power
consumption makes the SA612A excellent for battery-operated equipment. Networking
and other communications products can benefit from very low radiated energy levels
within systems. The SA612A is available in an 8-lead SO (surface-mounted miniature
package).
2. Features and benefits
Low current consumption
Low cost
Operation to 500 MHz
Low radiated energy
Low external parts count; suitable for crystal/ceramic filter
Excellent sensitivity, gain, and noise figure
3. Applications
Cordless telephone
Portable radio
VHF transceivers
RF data links
Sonobuoys
Communications receivers
Broadband LANs
HF and VHF frequency conversion
Cellular radio mixer/oscillator
NXP Semiconductors
SA612A
Double-balanced mixer and oscillator
4. Ordering information
Table 1.
Ordering information
Topside
marking
SA612A
Package
Name
SO8
Description
plastic small outline package; 8 leads; body width 3.9 mm
Version
SOT96-1
Type number
SA612AD/01
4.1 Ordering options
Table 2.
Ordering options
Orderable
part number
SA612AD/01,112
SA612AD/01,118
Package
Packing method
Minimum
order
quantity
2000
2500
Temperature
Type number
SA612AD/01
SO8
SO8
Standard marking
*IC’s tube - DSC bulk pack
Reel 13” Q1/T1
*Standard mark SMD
T
amb
=
40 C
to +85
C
T
amb
=
40 C
to +85
C
5. Block diagram
OSC_E
OSC_B
OUT_B
5
4
OUT_A
aaa-013372
V
CC
8
7
E
6
B
VOLTAGE
REGULATOR
OSCILLATOR
1
IN_A
2
IN_B
3
GND
Fig 1.
Block diagram
SA612A
All information provided in this document is subject to legal disclaimers.
© NXP Semiconductors N.V. 2014. All rights reserved.
Product data sheet
Rev. 3 — 4 June 2014
2 of 19
NXP Semiconductors
SA612A
Double-balanced mixer and oscillator
6. Pinning information
6.1 Pinning
SA612AD/01
IN_A
IN_B
GND
OUT_A
1
2
3
4
aaa-013371
8
7
6
5
V
CC
OSC_E
OSC_B
OUT_B
Fig 2.
Pin configuration for SO8
6.2 Pin description
Table 3.
Symbol
IN_A
IN_B
GND
OUT_A
OUT_B
OSC_B
OSC_E
V
CC
Pin description
Pin
1
2
3
4
5
6
7
8
Description
RF input A
RF input B
ground
mixer output A
mixer output B
oscillator input (base)
oscillator output (emitter)
supply voltage
SA612A
All information provided in this document is subject to legal disclaimers.
© NXP Semiconductors N.V. 2014. All rights reserved.
Product data sheet
Rev. 3 — 4 June 2014
3 of 19
NXP Semiconductors
SA612A
Double-balanced mixer and oscillator
7. Functional description
The SA612A is a Gilbert cell, an oscillator/buffer, and a temperature-compensated bias
network as shown in
Figure 3.
The Gilbert cell is a differential amplifier (IN_A and IN_B
pins) that drives a balanced switching cell. The differential input stage provides gain and
determines the noise figure and signal handling performance of the system.
18 kΩ
buffer
1.5 kΩ
1.5 kΩ
6
7
25 kΩ
4
5
BIAS
BIAS
2
1
BIAS
1.5 kΩ
1.5 kΩ
3
GND
aaa-013205
Fig 3.
Equivalent circuit
The SA612A is designed for optimum low-power performance. When used with the
SA614A as a 45 MHz cordless phone/cellular radio second IF and demodulator, the
SA612A is capable of receiving
119
dBm signals with a 12 dB S/N ratio. Third-order
intercept is typically
15
dBm (that is approximately +5 dBm output intercept because of
the RF gain). The system designer must be cognizant of this large signal limitation. When
designing LANs or other closed systems where transmission levels are high, and
small-signal or signal-to-noise issues are not critical, the input to the SA612A should be
appropriately scaled.
Besides excellent low-power performance well into VHF, the SA612A is flexible. The input,
output and oscillator ports support various configurations provided the designer
understands certain constraints, which are explained here.
The RF inputs (IN_A and IN_B pins) are biased internally. They are symmetrical. The
equivalent AC input impedance is approximately 1.5 k
3 pF through 50 MHz. IN_A and
IN_B pins can be used interchangeably, but they should not be DC biased externally.
Figure 4
shows three typical input configurations.
SA612A
All information provided in this document is subject to legal disclaimers.
© NXP Semiconductors N.V. 2014. All rights reserved.
Product data sheet
Rev. 3 — 4 June 2014
4 of 19
NXP Semiconductors
SA612A
Double-balanced mixer and oscillator
SA612A
SA612A
SA612A
1
2
1
aaa-013375
1
input
aaa-013374
2
2
aaa-013376
Ctune(xtal)
aaa-013378
a. Single-ended
tuned input
b. Balanced input
(for attenuation of
second-order
products)
c. Single-ended
untuned input
Fig 4.
Input configuration
The mixer outputs (OUT_A and OUT_B pins) are also internally biased. Each output is
connected to the internal positive supply by a 1.5 k resistor. This permits direct output
termination yet allows for balanced output as well.
Figure 5
shows three single-ended
output configurations and a balanced output.
CFU455
or equivalent
12 pF
5
5
SA612A
SA612A
Filter: K&L 38780 or equivalent
Ctune(xtal) matches 3.5 kΩ to next stage
4
aaa-013377
a. Single-ended ceramic filter
b. Single-ended crystal filter
4
5
SA612A
SA612A
4
4
5
aaa-013379
aaa-013380
c. Single-ended IFT
Fig 5.
Output configuration
d. Balanced output
SA612A
All information provided in this document is subject to legal disclaimers.
© NXP Semiconductors N.V. 2014. All rights reserved.
Product data sheet
Rev. 3 — 4 June 2014
5 of 19
