MAX3510EEP Maxim Integrated Products, MAX3510EEP Datasheet - Page 7

• Manufacturer Part Number: MAX3510EEP
• Description: RF Amplifier
• Manufacturer: Maxim Integrated Products
• Type: General Purpose Amplifierr

Specifications of MAX3510EEP

• Operating Frequency: 65 MHz
• Bandwidth: 100 MHz
• Supply Current: 109 mA
• Maximum Power Dissipation: 1067 mW
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Number Of Channels: 1 Channel
• Case: SSOP
• Dc: 00+

Figure 1. Functional Diagram
The following sections describe the blocks shown in the
functional diagram (Figure 1).
The programmable-gain amplifier (PGA) consists of the
variable-gain amplifier (VGA) and the digital-to-analog
converter (DAC), which provide better than 52dB of
output level control in 1dB steps.
The PGA is implemented as a programmable Gilbert-
cell attenuator. It uses a differential architecture to
achieve maximum linearity. The gain of the PGA is
determined by a 6-bit word (D5–D0) programmed
through the serial data interface (Tables 2 and 3).
Specified performance is achieved when the input is
driven differentially. The device may be driven single-
ended; however, a slight increase in even-order distor-
tion may result at low output levels. To drive the device
in this manner, one of the input pins must be capaci-
tively coupled to ground. Use a capacitor value large
enough to allow for a low-impedance path to ground at
the lowest frequency of operation. For operation down
to 5MHz, a 0.001µF capacitor is suggested.
Programmable-Gain Amplifier
_______________________________________________________________________________________
SHDN
V
VIN+
Detailed Description
VIN-
CC
1
PGA BIAS
CELL
SERIAL DATA INTERFACE
D/A CONVERTER
CS SDA SCLK
MAX3510
Upstream CATV Amplifier
The power amplifier is a Class A differential amplifier
capable of driving +64dBmV differentially. This archi-
tecture provides superior even-order distortion perfor-
mance but requires that a transformer be used to
convert to a single-ended output. In transmit-disable
mode, the power amplifier is shut off. An internal resis-
tor is placed across the output, so that the output
impedance remains matched when the amplifier is in
transmit-disable mode. Disabling the output devices
also allows the lowest standby noise.
To achieve the proper load line, the output impedance
of the power amplifier is 300Ω differential. To match this
output impedance to a 75Ω load, the transformer must
have a turns ratio (voltage ratio) of 2:1 (4:1 impedance
ratio).
The differential amplifier is biased directly from the +5V
supply using the center tap of the output transformer.
This provides a significant benefit when switching
between transmit mode and transmit-disable mode.
Stored energy due to bias currents will cancel within
the transformer and prevent switching transients from
reaching the load.
GENERATOR
RAMP
POWER
AMP
BIAS
VOUT-
VOUT+
CEXT2
V
TXEN
CEXT1
CC
2
Power Amplifier
7