Philips Semiconductors RF Communications Products

Product specification

SA601

Low voltage LNA and mixer - 1GHz

December 15, 1994

4

Figure 1. Application Circuit

1

2

3

4

5

6

7

8

9

10

20

19

18

17

16

15

14

13

12

11

Vcc

GND

LNA IN

GND

GND

MIXER PD

GND

LO IN

LO IN

Vcc

GND

LNA OUT

GND

MIXER IN

GND

MIXER OUT

MIXER OUT

GND

GND

Vcc

LNA IN

C1

C15

L1

56nH

C2

2.7pF

100pF

C11

100pF

C12

2.2pF

LNA OUT

C10

100pF

MIXER IN

C9

4.7pF

C13

100pF

270nH

C6

8.2pF

L = 110 mils

L = 95 mils

w = 15 mils

w = 15 mils

VCC

1

µF

100pF

SA601

C4

U1

VCC

J1

C14

100nF

J2

EXT LO

(-7dBm, 964MHz)

J5

L = 190 mils

w = 15 mils

J4

VCC

18pF

2.2k

C8

100nF

MIXER OUT

J3

(50

Ω, 83MHz)

C3

100pF

33pF

L3

L2

470nH

R2

C5

C7

L = 535 mils

w = 10 mils

L = 535 mils

w = 10 mils

*

**

**

** *

CIRCUIT TECHNOLOGY

LNA

Impedance Match: Intrinsic return loss at the input and output ports

is 7dB and 9dB, respectively. With no external matching, the

associated LNA gain is

≈10dB and the noise figure is ≈1.4dB.

However, the return loss can be improved at 881MHz using

suggested L/C elements (Figure 1) as the LNA is unconditionally

stable.

Noise Match: The LNA achieves 1.6dB noise figure at 881MHz

Temperature Compensation: The LNA has a built-in temperature

compensation scheme to reduce the gain drift to 0.003dB/

°C from

–40

°C to +85°C.

Supply Voltage Compensation: Unique circuitry provides gain

stabilization over wide supply voltage range. The gain changes no

LO Drive Level: Resistor R1 can be replaced by an inductor of

4.7nH and C13 should be adjusted to achieve a good return loss at

the LO port. Under this condition, the mixer will operate with less

than -10dBm LO drive.

IP3 Performance: C9 between Pin 16 and ground can be removed

to introduce 3dB mismatch loss, while improving the IP3 to +3dBm.

The associated noise figure is 11dB.

Mixer

Input Match: The mixer is configured for maximum gain and best

noise figure. The user needs to supply L/C elements to achieve this

performance.

Power Gain: The gain can be increased by approximately 1.5dB by

placing R2 across C7, instead of C5.

Power Down: The mixer can be disabled by connecting Pin 7 to

ground. When the mixer is disabled, 3mA is saved.

Power Combining: The mixer output circuit features passive

power combining (patent pending) to optimize conversion gain and

noise figure performance without using extra DC current or

degrading the IP3. For IF frequencies significantly different than

83MHz, the component values must be altered accordingly.

Filter Interface: For system integration where a high impedance

filter of 1k

Ω is to be cascaded at the mixer IF output, capacitors C5

and C6 need to be changed to 27pF and 1000pF, respectively.