ADL5331ACPZ-R7 Analog Devices Inc, ADL5331ACPZ-R7 Datasheet - Page 13

• Manufacturer Part Number: ADL5331ACPZ-R7
• Description: Broadband Differential VGA
• Manufacturer: Analog Devices Inc

Specifications of ADL5331ACPZ-R7

• Current - Supply: 240mA
• Frequency: 1MHz ~ 1.2GHz
• Gain: 15dB
• Noise Figure: 9dB
• Package / Case: 24-VFQFN, CSP Exposed Pad
• Rf Type: CATV
• Test Frequency: 900MHz
• Voltage - Supply: 4.75 V ~ 5.25 V
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: ADL5331ACPZ-R7; ADL5331ACPZ-R7TR

For the AGC loop to remain in equilibrium, the
track the envelope of the output signal of the ADL5331 and
provide the necessary voltage levels to the gain control input
of the ADL5331. Figure 21 shows an oscilloscope of the AGC
loop depicted in Figure 19. A 100 MHz sine wave with 50% AM
modulation is applied to the ADL5331. The output signal from the
VGA is a constant envelope sine wave with amplitude corres-
ponding to a setpoint voltage at the AD8319 of 1.3 V. The gain
control response of the AD8319 to the changing input envelope
is also shown in Figure 21.
Figure 22 shows the response of the AGC RF output to a pulse
on VSET. As VSET decreases from 1.5 V to 0.4 V, the AGC loop
responds with an RF burst. In this configuration, the input signal to
the ADL5331 is a 1 GHz sine wave at a power level of −15 dBm.
2
3
1
Figure 21. Oscilloscope Showing an AM Modulated Input Signal and the
CH3 250mV Ω
CH1
AD8319 OUTPUT
AM MODULATED INPUT
ADL5331 OUTPUT
250mV Ω
CH2 200mV
Response from the AD8319
T
T
M2.00ms
AD9789
Figure 23. Block Diagram of AD9789 interface to ADL5331 in a DOCSIS Type Application
T
DAC
0.00000s
16mA
16mA
A CH4
AD8319
70Ω
1.80V
must
25Ω
Rev. 0 | Page 13 of 16
VGA
50Ω
Response time and the amount of signal integration are con-
trolled by CLPF. This functionality is analogous to the feedback
capacitor around an integrating amplifier. While it is possible
to use large capacitors for CLPF, in most applications, values
under 1 nF provide sufficient filtering.
More information on the use of AD8319 in an AGC application
can be found in the AD8319 data sheet.
CMTS TRANSMIT APPLICATION
Interfacing to AD9789
Because of its broadband operating range, the ADL5331 VGA
can also be used in direct-launch cable modem termination
systems (CMTS) applications in the 50 MHz to 860 MHz cable
band. The ADL5331 makes an excellent choice as a post-DAC
VGA in a CMTS application when used with the Analog
Devices AD9789 wideband DAC. The AD9789 also contains
digital signal processing specifically designed to process
DOCSIS type CMTS signals. A typical AD9789-to-ADL5331
interface is shown in Figure 23.
2
CH3 200mV Ω
20Ω
Figure 22. Oscilloscope Showing theResponse Time of the AGC Loop
5V
TERMINATION
CH2 500mV
SERIES
55Ω
M 4.0µs 12.5MS/s 80.0ns/pt
A CH1
150mV
t1: 4.48µs
t2: 2.4µs
Δt: –2.08µs
1/Δt: –480.8kHz
MEAN(C1) 440.3mV
AMPL(C1) 3.36V
AMPL(C2) 900mV
CURS1 POS
CURS2 POS
ADL5331
4.48µs
2.4µs