Datasheet LT5554 (Analog Devices)
| Manufacturer | Analog Devices |
| Description | Broadband Ultra Low Distortion 7-Bit Digitally Controlled VGA |
| Pages / Page | 32 / 1 — FEATURES. DESCRIPTION. APPLICATIONS. TYPICAL APPLICATION. OIP3 and SFDR … |
| File Format / Size | PDF / 619 Kb |
| Document Language | English |
FEATURES. DESCRIPTION. APPLICATIONS. TYPICAL APPLICATION. OIP3 and SFDR vs Frequency
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LT5554 Broadband Ultra Low Distortion 7-Bit Digitally Controlled VGA
FEATURES DESCRIPTION
n 1GHz Bandwidth at all Gains The LT®5554 is a 7-bit digitally controlled programmable n 48dBm OIP3 at 200MHz, 2VP-P into 50Ω, gain (PG) amplifi er with 16dB gain control range. It ROUT = 100Ω consists of a 50Ω input variable attenuator, followed by n –88dBc IMD3 at 200MHz, 2VP-P into 50Ω, a high linearity variable transconductance amplifi er. The ROUT = 100Ω coarse 4dB input attenuator step is implemented via 2-bits n 1.4nV/√Hz Input-Referred-Noise (RTI) of digital control (PG5, PG6). The fi ne transconductance n 20dBm Output P1dB at 70MHz, ROUT = 130Ω amplifi er 0.125dB step within 3.875dB gain control range n 2dB to 18dB Gain Range (ROUT = 50Ω) is set via 5-bits digital control (PG0 to PG4). The LT5554 n 0.125dB Gain Step Size gain control inputs (PGx) and the STROBE input can be n 30ps Group Delay Variation directly coupled to TTL or ECL drivers. The seven parallel n 5ns Fast Gain Settling Time gain control inputs time skew can be eliminated by using n 5ns Fast Overdrive Recovery the STROBE input positive transition. n –80dB Reverse Isolation The internal output resistor RO = 400Ω limits the maxi- mum overall gain to 36dB for open outputs. The internal
APPLICATIONS
circuitry of open output collectors enables the LT5554 to be unconditionally stable over any loading conditions (in- n Differential ADC Driver cluding external SAW fi lters) and provides –80dB reverse n IF Sampling Receivers isolation at 300MHz. n VGA IF Power Amplifi er n 50Ω Driver The LT5554 is internally protected during overdrive and n Instrumentation has an on-chip power supply regulator. L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other With 0.125dB step resolution and 5ns settling time, the trademarks are the property of their respective owners. LT5554 is suitable in applications where continuous gain control is required.
TYPICAL APPLICATION OIP3 and SFDR vs Frequency
132 49 ROUT = 50Ω 5V VCC MODE 0.1μF 130 46 IN+ OIP3 (dBm) OIP3 – RF IF IF DEC BPF ADC INPUT BPF AMPLIFIER LT5554 + IN– SFDR (dBm/Hz) 128 43 LO 0.1μF 7 BITS 5554 TA01 PGx GAIN CONTROL SFDR CDEC 0.1μF STROBE 126 40 0 50 100 150 200 FREQUENCY (MHz) 5554 TA01b 5554f 1
FEATURES DESCRIPTION
n 1GHz Bandwidth at all Gains The LT®5554 is a 7-bit digitally controlled programmable n 48dBm OIP3 at 200MHz, 2VP-P into 50Ω, gain (PG) amplifi er with 16dB gain control range. It ROUT = 100Ω consists of a 50Ω input variable attenuator, followed by n –88dBc IMD3 at 200MHz, 2VP-P into 50Ω, a high linearity variable transconductance amplifi er. The ROUT = 100Ω coarse 4dB input attenuator step is implemented via 2-bits n 1.4nV/√Hz Input-Referred-Noise (RTI) of digital control (PG5, PG6). The fi ne transconductance n 20dBm Output P1dB at 70MHz, ROUT = 130Ω amplifi er 0.125dB step within 3.875dB gain control range n 2dB to 18dB Gain Range (ROUT = 50Ω) is set via 5-bits digital control (PG0 to PG4). The LT5554 n 0.125dB Gain Step Size gain control inputs (PGx) and the STROBE input can be n 30ps Group Delay Variation directly coupled to TTL or ECL drivers. The seven parallel n 5ns Fast Gain Settling Time gain control inputs time skew can be eliminated by using n 5ns Fast Overdrive Recovery the STROBE input positive transition. n –80dB Reverse Isolation The internal output resistor RO = 400Ω limits the maxi- mum overall gain to 36dB for open outputs. The internal
APPLICATIONS
circuitry of open output collectors enables the LT5554 to be unconditionally stable over any loading conditions (in- n Differential ADC Driver cluding external SAW fi lters) and provides –80dB reverse n IF Sampling Receivers isolation at 300MHz. n VGA IF Power Amplifi er n 50Ω Driver The LT5554 is internally protected during overdrive and n Instrumentation has an on-chip power supply regulator. L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other With 0.125dB step resolution and 5ns settling time, the trademarks are the property of their respective owners. LT5554 is suitable in applications where continuous gain control is required.
TYPICAL APPLICATION OIP3 and SFDR vs Frequency
132 49 ROUT = 50Ω 5V VCC MODE 0.1μF 130 46 IN+ OIP3 (dBm) OIP3 – RF IF IF DEC BPF ADC INPUT BPF AMPLIFIER LT5554 + IN– SFDR (dBm/Hz) 128 43 LO 0.1μF 7 BITS 5554 TA01 PGx GAIN CONTROL SFDR CDEC 0.1μF STROBE 126 40 0 50 100 150 200 FREQUENCY (MHz) 5554 TA01b 5554f 1
