Datasheet Analog Devices AD8369

45 dB Digitally Controlled VGA
LF to 600 MHz
AD8369
FEATURES
Digitally Controlled Variable Gain in 3 dB Steps
–5 dB to +40 dB (RL = 1 k⍀)
–10 dB to +35 dB (RL = 200 ⍀)
Less than 0.2 dB Flatness over a +20 MHz Bandwidth
up to 380 MHz
4-Bit Parallel or 3-Wire Serial Interface
Differential 200 ⍀ Input and Output Impedance
Single 3.0 V–5.5 V Supply
Draws 37 mA at 5 V
Power-Down VS/2), any
changes in the parallel data will result in a change in the gain,
after propagation delays. This is referred to as the transparent
mode of operation. If DENB is held low, the last 4-bit word in
the gain control register will remain latched regardless of the signals
at the data inputs. Noise and Distortion It is a common aspect of this style of VGAs, however implemented, that the effective noise figure worsens as the gain is
reduced. The AD8369 uses a fixed gain amplifier, having a certain
invariant noise spectral density, preceded by an attenuator.
Thus, the noise figure increases simply by 6 dB per tap point,
from a starting point of 7 dB at full gain. …