Document
PRELIMINARY
AIC1840/1841
LOW-NOISE, REGULATED GaAsFET BIAS
SPEC NO: DS-1840-P2
! FEATURES
" Low Output Noise: 2mV Ripple. " Work with Small Capacitors (as Low as 0.22µF). " Fixed -2V or Adjustable Output. " 2.5V to 6.5V Input Voltage Range. " Switching Frequency: 104KHz in Normal Operation. " 1µA Maximum in Shutdown Mode.
! APPLICATIONS
" Cellular Phones. " GaAsFET Power Amplifier Modules. " Personal Communicators and PDAs. " Wireless Data Loggers. " LCD Bias Contrast Control. " Regulated Negative Power Supplies.
! DESCRIPTION
The AIC1840/1841 is a switched-capacitor voltage inverter that generates a regulated fixed -2.0V or externally adjustable output. An internal linear post-regulator reduces the output voltage ripple to less than 2mV, making the AIC1840/1841 excellent for use as bias voltage generator for transmitter GaAsFETs in portable RF and cellular telephone applications. The operation voltage is as low as 2.5V.
The AIC1840/1841 offers a -2V preset output as well as a -1.3V to -3.0V adjustable output. Input voltage range for AIC1840/1841 is 2.5V to 6.5V. Output current is 5mA at VOUT= -2V and with VIN≥2.5V. Quiescent current is 510µA at VIN=3.6V and reduces to less than 1µA in shutdown mode (3µA max. for the AIC1841).
! TYPICAL APPLICATION CIRCUIT
The AIC1840 has an active-low shutdown input, while the AIC1841 has an active-high shutdown input.
VBAT (+2.5 ~ +6.5V) VTX
C3 3.3µF
+
C8 L1
C9
RF INPUT 8
RF POWER AMPLIFIER
L2 T1
C1 3.3µF
+
1 2
VDD CAPP VOUT
6 VOUT(VGS)= -2.0V
CAPN
C4
3 AIC1841
3.3µF + C5
C2 3.3µF
VNN
5
4 FB
SHDN
GND
+
7
VSHDN
R1 C6
C7
T2
C11 C10
RF OUTPUT
Bias Generator for GaAsFET Power Amplifier
! ORDERING INFORMATION
AIC1840 XX AIC1841 XX
PACKAGE TYPE N: PLASTIC DIP S: SMALL OUTLINE
TEMPERATURE RANGE C: 0°C~+70°C
ORDER NUMBER
AIC1840CN AIC1841CN (PLASTIC DIP)
AIC1840CS AIC1841CS (PLASTIC SO)
PIN CONFIGURATION
TOP VIEW CAPP 1 CAPN 2 VNN 3 SHDN 4
(AIC1840) *SHDN (AIC1841)
8 VDD 7 GND 6 VOUT 5 FB
ANALOG INTEGRATIONS CORPORATION
www.analog.com.tw
4F, 9 Industry E. 9th Road, Science-based Industrial Park , Hsinchu, Taiwan, R.O.C. TEL: (8863)577-2500 FAX:(8863)577-2510
1
AIC1840/1841
LOW-NOISE, REGULATED GaAsFET BIAS
SPEC NO: DS-1840-P2
! ABSOLUTE MAXIMUM RATINGS
Supply Voltage ......................................................……………..................…............. 7V Operating Temperature Range ....................................………...................... -25°C~80°C Storage Temperature Range ...............................……………...................... -65°C~150°C
! TEST CIRCUIT
VIN
1 CAPP + 1µF
C1
2 CAPN
8 VDD
+
7 GND
1µF C3
VIN
1µF + C2
AIC1840/1841
3 VNN
6 VOUT
C4
10µF
4 SHDN SHDN
FB 5
+
VOUT=-2V RL
! ELECTRICAL CHARACTERISTICS (VIN=3.6V, Ta=25°C, unless otherwise specified.)
PARAMETER
Supply Voltage Range Output Voltage Output Voltage Adjustment Range Set Voltage Supply Current Shutdown Mode Current
Output Load Regulation Output Ripple Oscillator Frequency Shu.