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RF9678 Schematic ( PDF Datasheet ) - RF Micro Devices

Teilenummer RF9678
Beschreibung W-CDMA TRANSMIT MODULATOR AND IF AGC
Hersteller RF Micro Devices
Logo RF Micro Devices Logo 




Gesamt 16 Seiten
RF9678 Datasheet, Funktion
Preliminary
RF9678
5 W-CDMA TRANSMIT MODULATOR AND IF AGC
Typical Applications
• W-CDMA Systems
• EDGE Systems
• CDMA Systems
• TDMA Systems
Product Description
The RF9678 is an integrated complete quadrature modu-
lator and IF AGC amplifier designed for the transmit sec-
tion of W-CDMA applications. It is designed to modulate
baseband I and Q signals, and amplify the resulting IF
signals while providing 55dB of gain control range. This
circuit is designed as part of RFMD’s single mode
W-CDMA Chipset, which also includes the RF2679
W-CDMA Receive IF AGC and Demodulator. The IC is
manufactured on an advanced Silicon Bi-CMOS process,
and is supplied in a16-pin leadless chip carrier.
Optimum Technology Matching® Applied
Si BJT
üSi Bi-CMOS
GaAs HBT
SiGe HBT
GaAs MESFET
Si CMOS
16 15 14 13
VGC 1
Gain Control
12 NC
VCC2 2
MOD+ 3
MOD- 4
5
S
Quad
/2
67
11 BG OUT
10 LO+
9 LO-
8
1.00
.80 0.85
.65
.60
.24 typ
.35
2 .23
4.00
sq.
.65
.30
4 PLCS
1.85
1.55 sq.
12°
max
.05
.01
NOTES:
.75
.50
.23
.13
.65 4 PLCS
Dimensions in mm.
1 Shaded Pin is Lead 1.
2
Dimension applies to plated terminal and is measured between 0.02 mm and
0.25 mm from terminal end.
3 Pin 1 identifier must exist on top surface of package by identification mark or
feature on the package body. Exact shape and size is optional.
4 Package Warpage: 0.05 max.
5 Die thickness allowable: 0.305 mm max.
Package Style: LCC, 16-Pin, 4x4
Features
• Digitally Controlled Power Down Modes
• 2.7V to 3.3V Operation
• Digital LO Quadrature Divider
• AGC Linearity/Current Consumption Var.
• IF AGC Amp with 55dB Gain Control
Ordering Information
RF9678
W-CDMA Transmit Modulator and IF AGC
RF9678 PCBA Fully Assembled Evaluation Board
Functional Block Diagram
RF Micro Devices, Inc.
7628 Thorndike Road
Greensboro, NC 27409, USA
Tel (336) 664 1233
Fax (336) 664 0454
http://www.rfmd.com
5
Rev A4 010622
5-91






RF9678 Datasheet, Funktion
RF9678
Ref Lvl
0 dBm
1.5
IMAG
T1
CF 380 MHz Meas Signal
SR 3.84 MHz Constellation
Demod
QPSK
A
EXT
Preliminary
5
-1.5
-1.875
Date:
6.FEB.2001 00:38:12
REAL
Figure 3. DC Offset Error (Carrier Feedthrough)
1.875
As is shown above, the EVM performance of a modulator can be correlated to it's carrier and sideband suppression per-
formance.
Unadjusted Performance
A Wideband CDMA signal is a noise-like signal occupying a channel bandwidth of 3.84MHz. When viewed on a spec-
trum analyzer the channel appears as a plateau raised above the noise floor (see Figure 4). In some cases, it is normal
to see a spike over the center of the W-CDMA plateau. This will occur when the absolute power level of the unadjusted
carrier feedthrough is higher than that of the W-CDMA channel level. The cause of this phenomenon can be understood
by examining the relative powers of the carrier signal and the W-CDMA channel power.
For Example, a 1Hz channel with a power of 0dBm has an absolute power level of 0dBm when viewed on a spectrum
analyzer. When that 0 dBm channel power is spread over a 3.84MHz channel, as in W-CDMA, it results in an absolute
channel power level of -65.8 dBm (-10*log (BW)). The absolute channel level displayed on the spectrum analyzer will
increase with the resolution bandwidth setting on the instrument although the integrated channel power will remain con-
stant. A resolution bandwidth (RBW) of 30kHz will increase the displayed power level by 44.7dB (+10*log(RBW)) to -
21.0dBm. With a desired signal output power of +2.0dBm and a carrier suppression of >20dBc, the absolute carrier level
can be as high as -18.0dBm (POUT-Suppression=Carrier Level). This will result in a 3dB carrier spike above the W-
CDMA channel level (see Figure 4). (Note: The relative height of the carrier spike above the W-CDMA channel level is
directly related to the RBW of the spectrum analyzer being used. The example above assumes a 30kHz RBW.)
The following equations may be used to calculate W-CDMA channel and carrier feedthrough levels.
W-CDMA Channel Level=Channel Power (Integrated over BW)-[10*log*(BW)]+[10*log*(RBW)]
Carrier Feedthrough=POUT (Desired Sideband)-Carrier Suppression
The next section describes a procedure that may be used to dramatically reduce carrier feedthrough by tuning or opti-
mizing the modulator input signals.
5-96
Rev A4 010622

6 Page









RF9678 pdf, datenblatt
RF9678
Preliminary
Evaluation Board Schematic
(Download Bill of Materials from www.rfmd.com.)
P1-1
P1
1 PD
P2-1
P2
1 VGC
P1-2 2 VCC1
2 GND
3 GND
CON3
3 GND
CON3
VPD
R3
1500
VCC
C4
10 nF
C3
10 nF
16 15 14 13
VGC
5
1
Gain Control
12
C2
R1 10 nF
39 k
T1 2
11
J1 50 Ω µstrip
1:4
Σ
MOD
NC
VCC
3
4
Qua
10
R2
d
/2
200
9
5678
C1
J2
I SIG+
J3
I SIG-
50 Ω µstrip
50 Ω µstrip
T2
4:1 50 Ω µstrip
J6
LO IN
50 Ω µstrip
50 Ω µstrip
J5
Q SIG-
J4
Q SIG+
5-102
Rev A4 010622

12 Page





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