LT5504EMS8 Linear Technology, LT5504EMS8 Datasheet - Page 6

• Manufacturer Part Number: LT5504EMS8
• Description: IC MEASURING RECEIVER RF 8-MSOP
• Manufacturer: Linear Technology

Specifications of LT5504EMS8

• Function: RF Measuring Receiver
• Frequency: 800MHz ~ 2.7GHz
• Rf Type: CDMA, GSM, TDMA, WCDMA
• Package / Case: 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
• Pin Count: 8
• Screening Level: Industrial
• Package Type: MSOP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

LT5504
APPLICATIO S I FOR ATIO
Figure 3 shows the output voltage vs RF input power
response for these two input terminations. The voltage
gain of the single-ended-to-differential conversion circuit
is:
where R
Thus, the output voltage curve in this case is shifted to the
left by about 3dB.
Table 1. The Component Values of Matching Network L
and C
6
GAIN
S2
f
IF
Figure 2. RF Input Matching Network at 1900MHz
1900
2500
2700
900
(MHz)
IN
START: 100MHz
=
Figure 1. Differential RF Input Impedance
= 100Ω is the narrow band input impedance.
20
1: 63.56Ω
2: 26.69Ω
3: 28.88Ω
–j98.05Ω
–j42.90Ω
–j27.76Ω
INPUT
900.00MHz
•
1.90GHz
2.50GHz
LOG
RF
U
MATCHING NETWORK
R
50
3.3pF
3.3pF
IN
C
C
L
S1
S2
3
SH
12.0
U
3.3
2.7
2.4
=
(nH)
2
3
dB
,
L
3.3nH
SH
W
1
5504 F02
TO RF
TO RF
C
S1
STOP:3GHz
/C
+
–
3.9
3.3
2.2
1.5
5504 F01
S2
U
(pF)
SH
, C
S1
Limiting Mixer and LPF
The amplified RF signal is down-converted using the
limiting mixer and LO signal. The resulting signal is filtered
by the 3rd-order, 450MHz, integrated low pass filter (LPF).
Only the desired IF signal is passed to the IF limiters for
further detection. Any other mixing products, including LO
feedthrough, are much reduced to maximize sensitivity.
The receiver’s sensitivity is thus defined by the LPF band-
width.
IF Limiter
The IF signal is then amplified through the multiple limiter
stages for further signal detection. All DC offsets, includ-
ing LO signal self-mixing, are eliminated by an internal DC
offset cancellation circuit. Nevertheless, care should be
taken in component placement and in PCB layout to
minimize LO coupling to the RF port.
Output Interface
The output interface of the LT55O4 is shown in Figure 4.
The output currents from the RF and IF detectors are
summed and converted into an output voltage, V
The maximum charging current available to the output
load is about 400µA. An internal compensation capacitor
C
capacitive output load. The slew rate is 80V/µs and the
small signal output bandwidth is approximately 5MHz
when the output is resistively terminated. When the output
is loaded with a large capacitor C
C
is used to guarantee stable operation for a large
Figure 3. The Output Voltage vs RF Input Power
2.5
2.0
1.5
1.0
0.5
0
–80 –70 –60 –50 –40 –30 –20 –10
f
RF
DIFFERENTIAL INPUT CIRCUIT
= 1.9GHz
WITH SINGLE-ENDED-TO-
WITH 1:1 INPUT TX
PIN (dBm)
L
, the slew rate is limited
5504 F03
0
10
OUT
5504f
.